Now officials have to make another potentially momentous decision, and quick: Will they give voters the chance to weigh in on transit expansion this November? Or wait until next year?

The answer is still unclear, even with a deadline looming.

“I’m not ready to get out in front of the rest of the board,” Commission Chairman Charlotte Nash said. “This is a very important decision, and the board as a whole needs to wrestle through the decision and get to the point where we know what the majority wants to do.”

While the commission votes necessary to call a referendum may be there in the end, there are still a lot of factors at play.

Most center around MARTA, its reputation, and the county’s ability to work out a suitable contract with it. Such a contract would have to be approved before a referendum was called.

Nash has said that, in order to hold a referendum on a 30-year transit funding sales tax this November, the decision would have to be made sometime in August.

Nash described it as “a transit tax that would be spent through a contract with MARTA.”

County leaders said it will all probably come down to money.

MARTA’s involvement presents an added layer for officials to weigh when considering a referendum. Gwinnett residents historically have been reticent about both mass transit in general and MARTA specifically; and while the former appears to have changed, it remains to be seen if the latter has.

Three of the five commission members would have to vote “yes” in order for a referendum to be called in November.

District 1 Commissioner Jace Brooks, whose district includes the Suwanee and Duluth areas, said this week his preference would be to move forward with a referendum this fall — “if we could work out a deal with MARTA that is favorable to Gwinnett County and meets our needs and all of the dollars are used to benefit Gwinnett County riders.”

District 2 Commissioner Lynette Howard said roughly the same thing: “I support having a referendum in November to allow Gwinnett residents to have a voice in the transit decision. But, before that happens, we must reach an agreement that provides the best benefit to our residents.”

District 3 Commissioner Tommy Hunter, on the other hand, said he hadn’t “given it much thought yet to be honest.”

And District 4 Commissioner John Heard said via text message on Monday that he “would not support” having a transit referendum in November. He did not respond to a request for further comment and was not present for Tuesday’s commission meetings.

Nash declined to say if the county was actively negotiating a contract with MARTA — but stressed multiple times that a partnership with the agency wouldn’t hinder the extensive plans Gwinnett already has in mind.

“Why would I agree to an arrangement that would inhibit our ability to put in place those kinds of things that we think are important for the community?” Nash said. “I have no reason to believe that there’d be push back from MARTA or any other provider associated with it.”

The non-binding transit development plan adopted by the commission Tuesday includes two tiers of recommendations for heavy rail. The first phase — which would be built within 30 years — calls for a roughly 4.5-mile heavy rail extension from Doraville to the area near I-85 and Jimmy Carter Boulevard.

The second phase suggests nearly seven more miles of rail from Jimmy Carter all the way up to the Gwinnett Place Mall area, where the county has already acquired land to expand its existing transit station. Funding for that stretch is not part of the roughly $5.4 billion of projected revenues included in the plan, which also includes several “bus rapid transit” lines and greatly expanded local bus service.

Each mile of heavy rail would likely cost at least $250 million, officials have said.

The roughly $5.4 billion in identified funding is based on estimates of money contributed by state and federal sources, on projected fare box revenues, and on the county’s residents approving of a new 30-year one-cent sales tax — whether that approval comes in November or further in the future.